Air heater and method of making the same



Aug. 11, 1931. H. J. KERR v AIR HEATER AND METHOD'OF MAKING THE SAME Filed May 17, 1927 INVENTOR A'ITGRNEY Patented Aug. 11, 1931 ETED HOWARD J. KERR, OF WESTFIELD, NEW JERSEY, ASSIGNOR TO THE BABCOCK & WILCOX COMPANY, OF BAYONNE, NEHV JERSEY, A CORPORATION OF NEW JERSEY AIR HEATER AND METHOD OF IVIAKING THE SAME Application filed May 17,

My invention relates to methods and means of fastening enamel tubes and the like to heaters in such a way as to avoid corrosion of the tubes, and will be best understood from the following description of an embodiment thereof taken in connection with the accompanying drawings, in which Fig. 1 is a plan of a portion of a heater or economizer showing a plurality of tube connections thereto, and Fig. 2 is a. cross section along the line 22 of Fig. 1.

Like reference characters indicate like parts throughout the views.

The tubes used in an air heater are quite susceptible to corrosion due to the presence of acids in the hot flue gases and due to the cleaning of the tubes with steam or hot water. Enamelling or coating of the tubes, on the surface or surfaces liable to corrosion, extends their period of life very materially and presents other advantages in the way of efficiency of the heater and the convenience of maintenance.

In the embodiment of my invention herein described header plates or tube sheets 10 and 11 form sides of a fine for hot gases and the fluid to be heated such as air or water passes through tubes 13. The tube sheets 10 and 11 are provided with oppositely disposed holes or bores 14 and 15 respectively for the connections of the tubes 13. Each hole 14 in the tube sheet 10 has an external counter bore or recess 16 to accommodate a flange 17 on each tube. As shown the enamel coating on the tube extends tothe end of the flange 17 and fits over the flange 18 that defines the hole 14. A washer or packing ring 19 retains the flange 17 of a tube rigidly in position in the tube sheet 10.

Each of the tubes 13 has a sliding sealed joint with the bore 15 in the header 11. Each hole 15 in the header plate is counterbored and tapped to hold apacking 21 and an externally threaded packing gland A su1table sealing fit, provided by adpzstment of 1927. Serial No. 192,148.

the movable gland, permits the tube to slide in the tube sheet 11 while being sealed against leakage of fluids around its connection.

The tube sheets 10 and 11 are secured in spaced relationship to one another by any suitable construction such as the other walls of the flue. The sheets may be portions of a flue as described or the tubes 13 themselves may be flue tubes carrying the hot gases. The fluid to be heated would then pass between the tube sheets 10 and 11 and flow around the flue tubes 13. The tubes 13 would then be enamelled interiorly. They may however be enamelled on both surfaces.

In construction, the tubes are cut to the desired length. The end of each tube is then expanded into a form to fit over the flange 18 of the tube sheet. The tube is then enamelled exteriorly, interiorly or both as desired and slid endways through a hole in the sheet 10 to seat the expanded flange against the bottom of the counterbore. The packing ring 19 is then forced into place and secured in any well known manner, holding the flange 17 in the counter-bore recess. The opposite ends of the tubes may if desired be secured rigidly into the other tube sheet 11. The tube sheets would, in that case, be retained in a rigid relationship by the tubes themselves.

lVhen the tubes are enamelled and fitted as shown, the heater may be erected without damage to the protective coating, and contact of flue gases or the use of steam or hot water to clean the tubes, will not affect the metal in the body of the tubes or injure the tubes adjacent the header connections. lVith the tubes thus protected both throughout their length and at their connections, the air heater should last indefinitely and be much more economical to maintain. The tubes themselves may freely expand or contract without stressing and chipping the enamel.

It will be obvious that changes may be made in the structure of my invention as shown Without departing from the spirit thereof.

I claim: In a fluid heater, a tube sheet having a 5 connterbored opening therethrotgh, a metal tube formed with" an outwardly extending flange seated in said counterbore, a coating of enamel on at least one surface of the tube and terminating on said flange, whereby a joint between the metal and the coating is formed on the flange, and a packing ring in the counterbore holding said flange on its seat and thereby covering said joint.

I-IOXVARD J. KERR. 

